FC0-U71 Tech Concepts and Terminology Practice Question
What is the decimal equivalent of the binary number 1101?
⚠ Common exam trap
The trap is misaligning the bit positions or forgetting that the leftmost bit in a 4-bit number is 8, not 16; candidates may incorrectly add 8+4+2+1=15 if they misread the bits.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
13
The binary number 1101 has four bits: the leftmost bit is the 8's place (2^3), then 4's (2^2), 2's (2^1), and 1's (2^0). Adding the values where bits are 1: 8 + 4 + 0 + 1 = 13. Therefore, the decimal equivalent is 13.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
15
Why it's wrong here
Binary 1101 evaluates as 8+4+0+1, giving 13, not 15. The value 15 corresponds to 1111, where all four bit positions are set. Reading 1101 as though every position were occupied is the tempting error, since 15 is the maximum for a four-bit number.
- ✓
13
Why this is correct
Binary 1101 converts by summing positional powers of two: 1×8 + 1×4 + 0×2 + 1×1, giving 8 + 4 + 0 + 1 = 13. This satisfies the stem's requirement for the decimal equivalent, since each bit's place value is added only where a 1 appears.
- ✗
10
Why it's wrong here
Binary 1101 equals 8 + 4 + 0 + 1, which is 13, not 10. It is tempting because 10 is the decimal value of binary 1010, so it would be correct if the question asked for the decimal equivalent of 1010.
- ✗
12
Why it's wrong here
Binary 1101 equals 8 + 4 + 0 + 1, which is 13, not 12. It is tempting because 12 is the decimal value of binary 1100, so it would be correct if the question asked for the decimal equivalent of 1100.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This FC0-U71 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the FC0-U71 exam.